Fingerprint verification is the process to determine whether two fingerprints are taken from the same finger. There are various methods of fingerprint verification. The most commonly used is called the fingerprint verification based on minutiae. Its working theory is as follows: (1) generate fingerprint templates by extracting minutiae (mainly refers to ridgeline ends and ridgeline bifurcations); (2) check the number of identical minutiae from the two templates; and (3) get verification results based on the number of identical minutiae.
As two fingerprints shall be placed on the same system in order to conduct fingerprint verification, therefore it is necessary to determine base point pair and align the two fingerprint images. There are various ways to search base point pair. The most commonly used method is to search base point pair in terms of minutiae type, minutiae direction and ridgeline curve.
The Chinese Patent case No. ZL88108482.4 (Publication No. CN1054225C) reveals an automatic fingerprint verification method. By comparing the minutiae of each fingerprint in the fingerprint database with that of the pre-calculated vector image of the to-be-verified fingerprint, the method is able to tell whether there is consistency between the fingerprint minutiae in database and the minutiae image of the to-be-verified fingerprint in terms of position and angle. The aforesaid fingerprint verification method is actually the improved version of the fingerprint verification method based on minutiae. The advantages of fingerprint verification method based on minutiae lie on the small size of fingerprint template and the high verification speed. Its disadvantages are: low efficiency in searching base point pair; inclination to lose true minutiae due to noise interference and image processing, which normally results in low identification rate; that it requests adequate number of minutiae to conduct valid verification, which normally results in limited application.